Nonwoven fiber webs frequently consist of a random yet homogeneous agglomeration of long and short fibers. Long fibers are fibers of both natural and synthetic origin that are suitable for textiles. They are longer than 0.25 inches and generally range between 0.5 and 2.5 inches in length. Short fibers are suitable for paper-making and are generally less than about 0.25 inches long, such as woodpulp fibers or cotton linters. It is known in the art that strong nonwoven webs can be made by rapidly and reliably blending inexpensive short fibers with strong long fibers.
Nonwoven fabrics are less costly than woven or knitted material, yet are more or less comparable in physical properties, appearance, and weight. Thus, inexpensive nonwoven fabrics are available for a wide variety of products, including, hand towels, table napkins, sanitary napkins, hospital clothing, draperies, cosmetic pads, etc. These nonwoven webs can be particularly advantageous when formed as a layered or composite material having a varying area in horizontal cross-section at various vertical locations.
Methods and machines for making nonwoven fluff pulp pads and pre-shaped absorbent products are known, but do not provide for selective blending and layering of pulp, textile, and particulate materials. In particular, providing webs with a shaped profile and/or layered construction is a desirable yet unattained attribute of web forming apparatus.
For example, U.S. Pat. No. 4,701,294 discloses an apparatus for airforming of webs. The apparatus includes a striking mechanism which feeds fiberized material into a web forming zone. A gas delivery system forces a gas stream along the fiberizing mechanism and into the web forming zone. The gas-fiber stream induces a supplementary gas flow and a steering mechanism guides the induced flow to direct the fibers toward selected areas of a condensing surface. This apparatus is inefficient in its operation. After passing the vanes which make up the steering mechanism, the air flow tends to return to a more even flow thus reducing the effect of the steering vanes. Therefore, sharp, even transitions cannot be made without placing the vanes directly above the condensing surface, which in turn increases the resistance to air flow to the condensing surface and turbulence at the condensing surface. Furthermore, the apparatus is limited to the use of a single fiber input, thus not permitting a blend of entrained fibers of differing types.